The correct option is D 2 J
We know the dimensional formula of energy,
[E]=[M1L2T−2]
For this, the unit of energy is 1 J.
If units of mass, length and time becomes 2 kg, 2 m and 2 s respectively then the new dimension of energy will be,
[E′]=[(2M)1(2L)2(2T)−2]
⇒[E′]=2[M1L2T−2]=2[E]
For this, the unit of energy will be 2 J.